[mechanickeith]

Small pipe does not make it quiet. It is a restriction & causes a severe loss of power. The muffler makes it quiet.

If my memory is correct, the inside dia at the outlet of the exhaust heat crossover adapter is 1 7/8 inch , 1 7/8 into the stock muffler & 1.5 inch from muffler to end of tail pipe. I have 2 cars that I have opened up the adapter outlet to 2 inches & ran a 2 1/4 inch pipe all the way out the back with a turbo muffler. Both are nice & quiet & made quite a bit more power. I did have to adjust the tune some for the less backpressure system.

I have 1 car that I removed the heat crossover all together & ran a 2.5 inch pipe from the exhaust manifold out to just in front of the right rear tire with a cheap glasspack. Quite a bit louder & ran much better.

I have also ran several with different style of headers. Most power I got was from a set of home made tri-y's I built. 1 7/8 primary pipes into 2 inch into 2.75 collector.